Tuning With An Air/Fuel Gauge

[chaseincats]

10 minutes ago, siteunseen said:

Looking at my picture I can see the middle vane is twisted a little. Wonder if that's what he did for some reason?

That's odd but I don't see how it would change anything.  I thought he bent the main support pin of WOT back.

[240260280]

I think the gaps can be changed a bit but you really have to alter when the cam (molded in the nylon) pushes on the center vane.

 

Edited March 17, 2021 by 240260280

[chaseincats]

47 minutes ago, 240260280 said:

I think the gaps can be changed a bit but you really have to alter when the cam (molded in the nylon) pushes on the center vane.

 

Why not just bend it back delaying when the center pin touches it?

[240260280]

That will give a little delay but if you bend it back too far, the contacts will  never close.

[chaseincats]

Ok gang, I have some pretty big findings.  Our issue is very much the TPS.

I was driving and getting in the high 13s after leaning it way out.  Frustrated, I pulled over and unplugged the TPS and immediately cruise changed from the 13s to the 17s.  The next plan (probably tomorrow) will be to configure the car to get low 15s (good target?) on cruise with the TPS unplugged, then fiddle with the TPS pins until I am able to get the proper cruise with it plugged in.

The problem very much is a lack of space between the cruise and WOT pin as I was barely able to hold it in the 14s with some really finite pedal work when it was plugged in.

[Captain Obvious]

Great input. Your findings with the WOT contacts are exactly what I meant with my #3 theory:

3) I think the WOT contacts close too early and the car runs too rich when they do.

It's clear from studying the system that the WOT contacts close long before you are actually at WOT. And that's why I was theorizing they closed too soon. But when gas is cheap, emissions standards are loose, and you want to sell sporty cars, you would err on the side of burning some extra fuel instead of the opposite. So going up a hill on the highway closes the WOT contacts. So what? It's just a little more gas.

Butterfly valves (like the throttle plate) are way way non-linear, so even though the plate isn't completely horizontal when the WOT contacts close, I was thinking that maybe you were pretty much there as far as max flow goes. But your A/F readings show that may not be the case.

So what are the alternatives? First alternative I got is the simple one... "Do you really need it at all?" By that, I mean... Can you tune the rest of the system such that the idle looks good, cruise looks good, and WOT is rich enough even without ever closing the WOT contacts?

If not, then the next alternative is what you already mentioned... Bend the WOT contacts as much as you can to delay the closing of the contacts. But as Blue mentioned, you can only do so much with that. Once the cam ramp is over, it's over. And bending beyond that will make it so the switch never closes at all.

If there's still not enough adjustment there, you may want to play around with different cams. That part should be a breeze for someone with a 3-D printer to whip out. Small and not particularly accurate. You could make a custom cam with more rotation between idle and WOT.

[siteunseen]

Or...bend the arm away farther. 6 of one, half a dozen of the other theory?

[chaseincats]

Thanks @Captain Obvious & @siteunseen

I definitely think I'll need to keep the TPS switch plugged in in some form as the car drives like a wet shoe without it lol

[240260280]

@Dr. 240Z & I were cruising on the highway at 60mph just on the idle circuit of his triple webers (no main jets installed). 

I think you may find the Bosch idle enrichment on the TVS is engaged at cruise as the throttle is opened very little at cruise.

You may wish to attack your optimization this way:

 

1. Configure:  Close AFM idle screw, disable TPS 

2. Set Cruise A/F: Adjust AFM spring to get your cruise at desired A/F ratio

2. Set Idle Enrichment Window: Enable TPS and adjust it so that it is not enriching at cruise. Disable WOT enrichment with tape on its contact as it will now come in earlier.

3. Set Idle A/F:   Use AFM idle air screw to get desired idle A/F ratio

 

You now have optimized 90% of your driving.  Next focus on the WOT (this is "under the rug" where you have swept any challenges from the above first two optimizations).  Perhaps modifying the TPS so that WOT enrichment comes in later is all that will need to be done. Good luck on this final adjustment.

[Captain Obvious]

9 hours ago, chaseincats said:

I definitely think I'll need to keep the TPS switch plugged in in some form as the car drives like a wet shoe without it lol

Well, another idea... I have not looked into any of the details about the actual circuit that performs the WOT or idle enrichment. The rest of the ECU is a black box of analog voodoo magic, and there's no reason to believe the enrichment circuits are anything other than more of the same. And because of that, there exists the possibility the amount of enrichment may actually be able to be adjusted by controlling the amount of resistance between the contacts.

In other words... The system normally works using two different resistance values - zero and infinite. Zero when the switch contacts are closed, and infinite at all other times. But what happens if you use a different value for when the switch is closed. Say 1K Ohms and infinite instead of zero and infinite?

If you put a resistor in series with the WOT contacts maybe it will still actuate the WOT enrichment, but not by as much as when it sees 0 Ohms?

You could try that at idle to see what happens. Compare what the A/F numbers do with 1) the WOT switch open, 2) switch closed, and 3) switch closed with some resistance in series. Just a thought if you wanted to give it a try.

[madkaw]

You would have a blast with a programmable ECU compared to this old Bosch !

When you get the numbers where you want and have recorded your AFR’s - make a valve timing change and see what that does to power and AFR’s . 
 

I’d also say you would be safe to go as lean as 13.2 at WOT if that gives you more adjustment somewhere else . 

[chaseincats]

58 minutes ago, Captain Obvious said:

Well, another idea... I have not looked into any of the details about the actual circuit that performs the WOT or idle enrichment. The rest of the ECU is a black box of analog voodoo magic, and there's no reason to believe the enrichment circuits are anything other than more of the same. And because of that, there exists the possibility the amount of enrichment may actually be able to be adjusted by controlling the amount of resistance between the contacts.

In other words... The system normally works using two different resistance values - zero and infinite. Zero when the switch contacts are closed, and infinite at all other times. But what happens if you use a different value for when the switch is closed. Say 1K Ohms and infinite instead of zero and infinite?

If you put a resistor in series with the WOT contacts maybe it will still actuate the WOT enrichment, but not by as much as when it sees 0 Ohms?

You could try that at idle to see what happens. Compare what the A/F numbers do with 1) the WOT switch open, 2) switch closed, and 3) switch closed with some resistance in series. Just a thought if you wanted to give it a try.

@240260280 Good plan, very methodical - I'll do that probably tomorrow evening.  Regarding the tape, I'm guessing you mean just electrical tape wrapped around the WOT contact, right?

@Captain Obvious Interesting idea, I might take that up down the road after everything is setup properly

@madkaw Good to know on the max leanness number for WOT thx